/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package org.codehaus.groovy.runtime.trampoline

import groovy.test.GroovyTestCase

/**
 * Test for the trampoline capabilities of closures.
 */
class TrampolineTest extends GroovyTestCase {
    public void testFactorial() {
        def fact
        fact = { int n, BigInteger accumulator ->
            n > 1 ? fact.trampoline(n - 1, n * accumulator) : accumulator
        }.trampoline()
        def factorial = {int n -> fact(n, 1 as BigInteger)}
        assert factorial(1)    == 1
        assert factorial(2)    == 2
        assert factorial(3)    == 6
        assert factorial(1000) == 402387260077093773543702433923003985719374864210714632543799910429938512398629020592044208486969404800479988610197196058631666872994808558901323829669944590997424504087073759918823627727188732519779505950995276120874975462497043601418278094646496291056393887437886487337119181045825783647849977012476632889835955735432513185323958463075557409114262417474349347553428646576611667797396668820291207379143853719588249808126867838374559731746136085379534524221586593201928090878297308431392844403281231558611036976801357304216168747609675871348312025478589320767169132448426236131412508780208000261683151027341827977704784635868170164365024153691398281264810213092761244896359928705114964975419909342221566832572080821333186116811553615836546984046708975602900950537616475847728421889679646244945160765353408198901385442487984959953319101723355556602139450399736280750137837615307127761926849034352625200015888535147331611702103968175921510907788019393178114194545257223865541461062892187960223838971476088506276862967146674697562911234082439208160153780889893964518263243671616762179168909779911903754031274622289988005195444414282012187361745992642956581746628302955570299024324153181617210465832036786906117260158783520751516284225540265170483304226143974286933061690897968482590125458327168226458066526769958652682272807075781391858178889652208164348344825993266043367660176999612831860788386150279465955131156552036093988180612138558600301435694527224206344631797460594682573103790084024432438465657245014402821885252470935190620929023136493273497565513958720559654228749774011413346962715422845862377387538230483865688976461927383814900140767310446640259899490222221765904339901886018566526485061799702356193897017860040811889729918311021171229845901641921068884387121855646124960798722908519296819372388642614839657382291123125024186649353143970137428531926649875337218940694281434118520158014123344828015051399694290153483077644569099073152433278288269864602789864321139083506217095002597389863554277196742822248757586765752344220207573630569498825087968928162753848863396909959826280956121450994871701244516461260379029309120889086942028510640182154399457156805941872748998094254742173582401063677404595741785160829230135358081840096996372524230560855903700624271243416909004153690105933983835777939410970027753472000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
    }

    public void testMutualRecursion() {
        def funB
        def funA = { int num -> num == 0 ? 0 : funB.trampoline(num - 1)}.trampoline()
        funB = { int num -> num == 0 ? 0 : funA.trampoline(num - 1)}.trampoline()
        assert 0 == funA(1000)
        assert 0 == funA(2000)
    }

    public void testMutualRecursionWithTrampolineOnFunAOnly() {
        def funB
        def funA = { int num -> num == 0 ? 0 : funB.trampoline(num - 1)}.trampoline()
        funB = { int num -> num == 0 ? 0 : funA.trampoline(num - 1)}
        assert 0 == funA(1000)
        assert 0 == funA(2000)
    }

    public void testMutualRecursionWithUserCallingTrampoline() {
        def funB
        def funA = { int num -> num == 0 ? 0 : funB.trampoline(num - 1)}
        funB = { int num -> num == 0 ? 0 : funA.trampoline(num - 1)}
        assert 0 == funA.trampoline(1000)()
        assert 0 == funA.trampoline()(2000)
    }
}
